Method for detecting guard-rail using lidar sensor and guard-rail detection device performing the method

ABSTRACT

A method for detecting a guard-rail on a road, which is performed by a guard-rail detection device, is provided. The method includes acquiring points around a lidar sensor from the lidar sensor, detecting ground points based on the acquired points, arranging, among the acquired points, first points that are different from the detected ground points in voxels forming a sphere, and detecting the guard-rail based on the voxels and the first points.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No.10-2021-0112085, filed on Aug. 25, 2021. The entire contents of theapplication on which the priority is based are incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to a method for detecting a guard-railusing a lidar sensor and a guard-rail detection device performing themethod.

BACKGROUND

A guard-rail generally indicates a structure installed on a road forpreventing accidents caused from a fall-down of a vehicle or a violationof the center line. The guard-rail is an important structure for theroad safety by preventing a secondary accident caused from a lanedeparture and a serious accident caused from the violation of the centerline.

Recognizing an accurate position of the vehicle (vehicle localization)is important in autonomous driving and an ADAS system in order to drivethe vehicle using sensors installed at the vehicle. It is possible torecognize a width of a lane and the number of lanes using theguard-rail, by which it is possible to generate a route for autonomousdriving. Further, it is also important to determine areas including theguard-rail in which the vehicle cannot be driven. In performing moreaccurate vehicle localization for autonomous driving, it is possible torecognize the position of the vehicle by comparing pre-existinginformation of the guard-rail stored in a high definition map withcurrent information of the guard-rail. Like this, the guard-rail is animportant regional characteristic that can be used to perform limitingthe areas in which the vehicle can be driven and to recognize theposition of the vehicle. The guard-rail usually exists at an edge of aroad or a bridge, but may be installed at a center of the road toprevent the violation of the center line. It is essential for autonomousdriving to detect the position of the guard-rail and to control thevehicle in consideration of the position of the guard-rail.

According to a conventional (existing) guard-rail detecting method, theguard-rail is detected by a camera. In the conventional method, aftersearching for drivable areas with camera, a boundary is detected as theguard-rail or the guard-rail is detected using information of an edge.However, this method has a drawback that the guard-rail is detected wellonly in the daytime of nice weather since the camera is greatlyinfluenced by a change of illuminance. Further, since there are manycases that a guard-rail shown by the camera has a similar characteristicwith a lane line, the camera may falsely detect the lane line as theguard-rail.

In contrast, a conventional (existing) guard-rail detecting method usinglidar data, a method of comparing between same layers based on the layerinformation of points. This method has a drawback that the algorithm canbe applied only after recognizing sensor input information or layerinformation and a drawback that the speed is low since it usesinformation of all the points.

Accordingly, there arises a demand for a guard-rail detecting methodwithout layer information or with a high speed.

SUMMARY

In view of the above, the present disclosure provides a method fordetecting a guard-rail on a road by using point data.

Technical objects to be achieved by the present disclosure are notlimited to those described above, and other technical objects notmentioned above may also be clearly understood from the descriptionsgiven below by those skilled in the art to which the present disclosurebelongs.

In accordance with an aspect of the present disclosure, there isprovided a method for detecting a guard-rail on a road, which isperformed by a guard-rail detection device, the method including:acquiring points around a lidar sensor from the lidar sensor; detectingground points based on the acquired points; arranging, among theacquired points, first points that are different from the detectedground points in voxels forming a sphere; and detecting the guard-railbased on the voxels and the first points.

Further, the detecting of the guard-rail may include: generating aplurality of voxel groups by classifying voxels, having a same thetadirection coordinate and a same phi direction coordinate, as a samegroup among the voxels in which the first points are arranged; selectingthe closest voxel from the lidar sensor among the voxels in each of theplurality of voxel groups as a directional representative voxel for eachof the plurality of voxel groups; determining whether the respectivedirectional representative voxels for the plurality of voxel groupssatisfy planeness; selecting, among the respective directionalrepresentative voxels for the plurality of voxel groups, directionalrepresentative voxels satisfying planeness as guard-rail candidatevoxels; and selecting a guard-rail candidate by connecting theguard-rail candidate voxels.

Further, the determining of whether the respective directionalrepresentative voxels for the plurality of voxel groups satisfyplaneness may include selecting, among a plurality of points positionedin each of the respective directional representative voxels for theplurality of voxel groups, a directional representative point for eachof the directional representative voxels.

Further, the determining of whether the respective directionalrepresentative voxels for the plurality of voxel groups satisfyplaneness may include: for each of the directional representativevoxels, selecting a first voxel that is a directional representativevoxel having a same phi direction coordinate as the correspondingdirectional representative voxel and having a theta direction coordinatethat is larger than that of the corresponding directional representativevoxel, and a second voxel that is a directional representative voxelhaving a same phi direction coordinate as the corresponding directionalrepresentative voxel and having a theta direction coordinate that issmaller than that of the corresponding directional representative voxel,and determining whether the corresponding directional representativevoxel satisfies a line fitting condition for a first straight linegenerated by a predetermined first rule in the theta direction;selecting a third voxel that is a directional representative voxelhaving a same theta direction coordinate as the correspondingdirectional representative voxel and having a phi direction coordinatethat is larger than that of the corresponding directional representativevoxel, and a fourth voxel that is a directional representative voxelhaving a same theta direction coordinate as the correspondingdirectional representative voxel and having a phi direction coordinatesmaller than that of the corresponding directional representative voxel,and determining whether the corresponding directional representativevoxel satisfies a line fitting condition for a second straight linegenerated by a predetermined second rule in the phi direction; and, whenthe corresponding directional representative voxel satisfies the linefitting condition for the first straight line and the line fittingcondition for the second straight line, determining that thecorresponding directional representative voxel satisfies planeness.

Further, the first straight line may be generated by connecting thedirectional representative point of the first voxel and the directionalrepresentative point of the second voxel, and the determining of whetherthe corresponding directional representative voxel satisfies the linefitting condition for the first straight line may include determiningthat the corresponding directional representative voxel satisfies theline fitting condition for the first straight line when a distancebetween the directional representative point of the correspondingdirectional representative voxel and the first line is equal to or lessthan a predetermined distance.

Further, the second straight line may be generated by connecting thedirectional representative point of the third voxel and the directionalrepresentative point of the fourth voxel, and the determining of whetherthe corresponding directional representative voxel satisfies the linefitting condition for the second straight line may include determiningthat the corresponding directional representative voxel satisfies theline fitting condition for the second straight line when a distancebetween the directional representative point of the correspondingdirectional representative voxel and the second line is equal to or lessthan a predetermined distance.

Further, the first voxel and the second voxel may be adjacent to thecorresponding directional representative voxel, and the third voxel andthe fourth voxel may be adjacent to the corresponding directionalrepresentative voxel.

Further, the guard-rail candidate selected in the selecting of theguard-rail candidate may be formed by connecting the guard-railcandidate voxels adjacent to each other in an extended direction.

The method may further include detecting, as the guard rail, theguard-rail candidate having a width in a direction parallel to a groundand perpendicular to the extended direction and having a length in theextended direction, the width being equal to or less than apredetermined width and the length being equal to or larger than apredetermined length.

In accordance with another aspect of the present disclosure, there isprovided a guard-rail detection device including: a lidar sensorconfigured to acquire points around the lidar sensor; and a processorconfigured to detect ground points based on the acquired points,arrange, among the acquired points, first points that are different fromthe detected ground points in voxels forming a sphere, and detect aguard-rail based on the voxels and the first points.

In accordance with still another aspect of the present disclosure, thereis provided a non-transitory computer-readable storage medium storingcomputer-executable instructions which cause, when executed by aprocessor, the processor to perform a method for detecting a guard-railon a road by using a guard-rail detection device, the method including:acquiring points around a lidar sensor from the lidar sensor; detectingground points based on the acquired points; arranging, among theacquired points, first points that are different from the detectedground points in voxels forming a sphere; and detecting the guard-railbased on the voxels and the first points.

According to the embodiment of the present disclosure, by arrangingpoint data received from a lidar sensor in voxels forming a sphere anddetecting the guard-rail by units of voxels, it is possible to rapidlyand accurately detect the guard-rail without using all of the pointdata. That is, it is possible to increase the safety of autonomousdriving by accurately detecting the guard-rail, and it is possible toprovide a processing method suitable for operating a real time controlsystem by rapidly processing the data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a guard-rail detection deviceaccording to an embodiment of the present disclosure.

FIG. 2A is an example illustrating a position and a shape of theguard-rail installed on a road.

FIG. 2B is an example illustrating a position and a shape of theguard-rail installed on a road.

FIG. 3A illustrates voxels forming a sphere generated according to theembodiment of the present disclosure.

FIG. 3B illustrates voxels forming a sphere generated according to theembodiment of the present disclosure.

FIG. 4 illustrates a result of detecting directional representativevoxels after eliminating a ground (ground surface) according to theembodiment of the present disclosure.

FIG. 5 illustrates a method for selecting directional representativepoints according to the embodiment of the present disclosure.

FIG. 6A illustrates a method for determining whether a directionalrepresentative voxel satisfies straightness in a theta direction and aphi direction according to the embodiment of the present disclosure.

FIG. 6B illustrates a method for determining whether a directionalrepresentative voxel satisfies straightness in a theta direction and aphi direction according to the embodiment of the present disclosure.

FIG. 6C illustrates a method for determining whether a directionalrepresentative voxel satisfies straightness in a theta direction and aphi direction according to the embodiment of the present disclosure.

FIG. 7 illustrates guard-rail candidate voxels satisfying planenessaccording to the embodiment of the present disclosure.

FIG. 8 illustrates the guard-rail detected according to the embodimentof the present disclosure.

FIG. 9 is a block diagram for explaining the guard-rail detection devicein aspect of hardware.

FIG. 10 is a flowchart of a method for detecting the guard-railaccording to the embodiment of the present disclosure.

DETAILED DESCRIPTION

The advantages and features of exemplary embodiments of the presentdisclosure and methods of accomplishing them will be clearly understoodfrom the following description of the embodiments taken in conjunctionwith the accompanying drawings. However, the present disclosure is notlimited to those embodiments and is implemented in various forms. It isnoted that the embodiments are provided to make a full disclosure andalso to allow those skilled in the art to know the full scope of thepresent disclosure.

In the following description, well-known functions and/or configurationswill not be described in detail if they would unnecessarily obscure thefeatures of the disclosure. Further, the terms to be described below aredefined in consideration of their functions in the embodiments of thedisclosure and vary depending on a user’s or operator’s intention orpractice. Accordingly, the definition is made on a basis of the contentthroughout the present disclosure.

FIG. 1 is a block diagram illustrating a guard-rail detection deviceaccording to an embodiment of the present disclosure.

Referring to FIG. 1 , a guard-rail detection system 10 may include aguard-rail detection device 100 and a lidar sensor 200.

In the present disclosure, for the sake of convenience of description, acase where the guard-rail detection system 10 is installed in anautonomous vehicle (hereinafter simply referred to as a vehicle) ismainly described. However, the present disclosure is not limitedthereto. For example, the guard-rail detection system 10 may beinstalled in an unmanned moving object such as a drone or other movingobjects such as a vehicle, a motorcycle, a flight vehicle, and the likeas well as the autonomous vehicle.

In addition, in the present disclosure, a case where the lidar sensor200 is provided separately from the guard-rail detection device 100 totransmit point data to the guard-rail detection device 100 is mainlydescribed. However, the present disclosure is not limited thereto. Forexample, the guard-rail detection device 100 may include the lidarsensor 200. In this case, the lidar sensor 200 may transmit the pointdata to a point data receiving unit 110 which will be described laterthrough internal signaling.

The lidar sensor 200 may emit a laser beam (light pulse) in apredetermined direction and receive a reflected (or backscattered) laserbeam from surrounding terrain and objects. The lidar sensor 200 maycollect point data through the reflected laser beam. Here, the pointdata may be a point cloud of individual points belonging to a certaincoordinate system. In a three-dimensional coordinate system, a point isusually defined by X, Y, and Z coordinates, and is often used toindicate a surface of an object.

A guard-rail detection device 100 may receive the point data from thelidar sensor 200 and use the received point data to detect a guard-railaround the guard-rail detection device 100 or around the vehicle onwhich the guard-rail detection device 100 is mounted.

Specifically, the guard-rail detection device 100 may include a pointdata receiving unit 110, a ground elimination unit 120, a voxelgeneration unit 130, a representative point detection unit 140, aguard-rail candidate detection unit 150, and a guard-rail detection unit160, which are conceptually indicating functions for detecting theguard-rail.

The point data receiving unit 110 may receive the point data collectedby the lidar sensor 200. Then, the ground elimination unit 120 maydetect a ground on a road using the point data received by the pointdata receiving unit 110. The ground elimination unit 120 may detect theground using a known technique as a method for detecting the ground. Theknown technique includes various methods such as a plane fitting, aground detection based on a grid map, and the like. However, the presentdisclosure is not limited thereto, and the method for detecting theground may include additional various methods.

For example, the ground elimination unit 120 may solve a plane equationcorresponding to the ground through a plane fitting in the distributionof the received point data, calculate a distance between the plane andeach point of the point data, detect points on which the ground ispositioned by determining that points positioned close to the plane arethe points on which the ground is positioned, and eliminate the pointson which the ground is positioned

FIGS. 2A and 2B are examples illustrating a position and a shape of theguard-rail installed on a road.

Referring to FIG. 2A, the guard-rail 20 is positioned at an area that isnot covered by objects around the vehicle traveling on the road whenviewed from the lidar sensor 200.

Further, referring to FIG. 2B, the guard-rail may be positioned on animaginary plane extended in a direction which is perpendicular to theground (g).

Thus, according to the embodiment of the present disclosure, after theguard-rail detection device 100 receivies the point data from the lidarsensor 200, the guard-rail detection device 100 may determine that aspot on which the closest point to the lidar sensor 200 is positionedamong first points that are not determined as points corresponding tothe ground as the position of the guard-rail. Further, the guard-raildetection device 100 may determine whether the guard-rail is positionedon such a point using a characteristic that the guard-rail is positionedon the imaginary plane, and may detect the guard-rail.

FIGS. 3A and 3B illustrate voxels forming a sphere generated accordingto the embodiment of the present disclosure.

Referring to FIGS. 3A and 3B, the voxel generation unit 130 may generatevoxels forming a sphere and arrange the point data in the generatedvoxels. After that, the voxel generation unit 130 may store point datapositioned in each voxel.

For example, the voxel generation unit 130 may generate voxels forming asphere around the lidar sensor 200. For the sake of convenience ofdescription, a case where a sphere of the voxels is generated around thelidar sensor 200 that is a center of the sphere is described. However,the present disclosure is not limited thereto. The guard-rail detectiondevice 100 or a center of the vehicle may be positioned at the center ofthe sphere.

The coordinate system used in the voxels forming the sphere may includea distance component from the center indicated by rho, a directioncomponent indicated by theta and a direction component indicated by phi.Here, the theta direction may indicate a magnitude of an angle measuredin a clockwise direction from 0 degrees of x-axis on the x-y plane ofthe orthogonal coordinates system, which is parallel to the ground (g),and the phi direction may indicate a magnitude of an angle measured in aclockwise direction from 0 degrees of y-axis on the y-z plane of theorthogonal coordinates system, which is perpendicular to the ground (g).

Further, the voxel generation unit 130 may generate a plurality ofvoxels 40 by dividing the voxels into predetermined rho directioncomponent distance units, predetermined theta direction component units,and predetermined phi direction component units, and position the firstpoint data inside each voxel 40. Further, the voxel generation unit 130may indicate the coordinates of the voxel as “R_(k), T_(m), P_(n)” ifthe voxel is positioned in k^(th) position in the rho direction from thecenter, m^(th) position in the theta direction from x-axis, and n^(th)position in the phi direction from y-axis.

Then, the guard-rail detection device 100 may detect the guard-railwithout determining every point data and without layer information ofthe point data, using the generated voxels 40 and the first point datalocated inside the voxels 40.

A method for detecting guard-rail candidate voxels and a method fordetecting the guard-rail will be described below.

The representative point detection unit 140 may select each directionalrepresentative voxel among a plurality of voxels generated by the voxelgeneration unit 130, and detect each directional representative pointamong the first points located in each directional representative voxel.Here, each direction may be indicated as “T, P” direction including atheta direction component and a phi direction component except a rhodirection component.

More specifically, the representative point detection unit 140 mayclassify the voxels having the same theta direction coordinate and thesame phi direction coordinate in which the first points are positionedas the same group using the coordinates of each voxel, in order toselect each directional representative voxel. For example, therepresentative point detection unit 140 may classify the voxelspositioned in “T_(m), P_(n)” direction (i.e., positioned in m^(th)position in the theta direction from x-axis, and n^(th) position in thephi direction from y-axis) as the same group.

Then, the representative point detection unit 140 may select the closestvoxel from the center position in each generated group as thedirectional representative group. For example, if a voxel positioned ink^(th) position in the rho direction from the center is the voxellocated closest to the center position among a group of voxelspositioned in “T_(m), P_(n)” direction, the representative pointdetection unit 140 may select a voxel positioned in “R_(k), T_(m),P_(n)” as the directional representative voxel in “T_(m), P_(n)”direction.

Since there is generally no other object between the guard-rail on theroad and the vehicle V (or the lidar sensor 200), the guard-raildetection device 100 may detect the guard-rail based on the voxelclosest from the vehicle V or the lidar sensor 200 among the voxels inwhich the first points are positioned.

FIG. 4 illustrates a result of detecting directional representativevoxels after eliminating a ground according to the embodiment of thepresent disclosure.

Referring to FIG. 4 , the ground elimination unit 120 may eliminatepoints corresponding to the ground among the points received from thepoint data receiving unit 110, and the representative point detectionunit 140 may select the directional representative voxels among thevoxels generated by the voxel generation unit 130. For example, therepresentative point detection unit 140 may select voxels brightlyindicated as white color except the vehicle V as the directionalrepresentative voxels. Since, the directional representative voxels mayinclude other vehicles or other objects on the road except theguard-rail, the guard-rail detection device 100 may detect guard-railcandidate voxels among the directional representative voxels.

FIG. 5 illustrates a method for selecting directional representativepoints according to the embodiment of the present disclosure.

Referring to FIG. 5 , the representative point detection unit 140 maydetect one point from the first points located in each directionalrepresentative voxel as a directional representative point correspondingto each directional representative voxel. For example, therepresentative point detection unit 140 may detect the closest point 52from the lidar sensor 200 that may be positioned at the center of voxelsforming a sphere as the directional representative point, among thefirst points 51, 52 positioned in the directional representative voxel50. The directional representative point detected by the representativepoint detection unit 140 is not limited to this, and the directionalrepresentative point may be detected by other methods such as a methodof detecting the farthest point from the center of the voxels.

The representative point detection unit 140 may detect the directionalrepresentative point by pre-calculating the distance from the lidarsensor 200 positioned at the center in the course of generating thevoxels for the convenience of calculation.

FIGS. 6A and 6B illustrates a process for determining whether thedirectional representative voxel satisfies line fitting conditions for afirst straight line and a second straight line generated by a first ruleand a second rule in the theta direction and the phi direction, and FIG.6C illustrates a method for determining whether the directionalrepresentative voxel satisfies planeness according to the embodiment ofthe present disclosure.

The guard-rail candidate detection unit 150 may determine whether eachdirectional representative voxel satisfies the planeness. Further, inorder to determine whether each directional representative voxelsatisfies the planeness, the guard-rail candidate detection unit 150 maydetermine whether each directional representative voxel satisfies a linefitting condition for the first straight line 65 in the theta direction,and determine whether each directional representative voxel satisfies aline fitting condition for the second straight line 85 in the phidirection.

Referring to FIG. 6A, the guard-rail candidate detection unit 150 mayselect a planeness determination voxel 50, a first voxel 60 which is adirectional representative voxel having the same phi directioncoordinate with the planeness determination voxel 50 and having a thetadirection coordinate smaller than the planeness determination voxel 50,and a second voxel 70 which is a directional representative voxel havingthe same phi direction coordinate as the planeness determination voxel50 and having a theta direction coordinate larger than the planenessdetermination voxel 50, and determine whether the planenessdetermination voxel 50 satisfies a line fitting condition for the firststraight line 65 in the theta direction. For example, if the planenessdetermination voxel 50 is positioned at (R_(k), T_(m), P_(n)), the firstvoxel 60 may be positioned at (R_(k), T_(m-1), P_(n)) which is adjacentto the planeness determination voxel 50, and the second voxel 70 may bepositioned at (R_(k), T_(m)+₁, P_(n)) which is adjacent to the planenessdetermination voxel 50.

More specifically, the guard-rail candidate detection unit 150 may firstgenerate the first straight line 65 connecting a directionalrepresentative point 62 of the first voxel 60 and a directionalrepresentative point 72 of the second voxel 70. Then, referring to FIG.6C, the guard-rail candidate detection unit 150 may calculate a distancebetween a directional representative point 52 of the planenessdetermination voxel 50 and a point extended downward from thedirectional representative point 52 of the planeness determination voxel50 to the first straight line 65. If the distance is equal to or lessthan a predetermined length, the guard-rail candidate detection unit 150may determine that the planeness determination voxel 50 satisfies theline fitting condition for the first straight line 65 in the thetadirection.

Referring to FIG. 6B, the guard-rail candidate detection unit 150 mayselect a planeness determination voxel 50, a third voxel 80 which is adirectional representative voxel having the same theta directioncoordinate as the planeness determination voxel 50 and having a phidirection coordinate smaller than the planeness determination voxel 50,and a fourth voxel 90 which is a directional representative voxel havingthe same theta direction coordinate as the planeness determination voxel50 and having a phi direction coordinate larger than the planenessdetermination voxel 50, and determine whether the planenessdetermination voxel 50 satisfies a line fitting condition for the secondstraight line 85 in the phi direction. For example, if the planenessdetermination voxel 50 is positioned at (R_(k), T_(m), P_(n)), the thirdvoxel 80 may be positioned at (R_(k), T_(m), P_(n-1)) which is adjacentto the planeness determination voxel 50, and the fourth voxel 90 may bepositioned at (R_(k), T_(m), P_(n+1)) which is adjacent to the planenessdetermination voxel 50.

More specifically, the guard-rail candidate detection unit 150 may firstgenerate the second straight line 85 connecting a directionalrepresentative point 82 of the third voxel 80 and a directionalrepresentative point 92 of the fourth voxel 90. Then, referring to FIG.6C, the guard-rail candidate detection unit 150 may calculate a distancebetween a directional representative point 52 of the planenessdetermination voxel 50 and a point extended downward from thedirectional representative point 52 of the planeness determination voxel50 to the second straight line 85. If the distance is equal to or lessthan a predetermined length, the guard-rail candidate detection unit 150may determine that the planeness determination voxel 50 satisfies theline fitting condition for the second straight line 85 in the phidirection.

The guard-rail candidate detection unit 150 may determine that adirectional representative voxel satisfying the line fitting conditionfor the first straight line 65 in the theta direction and the linefitting condition for the second straight line 85 in the phi directionsatisfies the planeness, and may detect directional representativevoxels satisfying the planeness as guard-rail candidate voxels.

FIG. 7 illustrates guard-rail candidate voxels satisfying planenessaccording to the embodiment of the present disclosure.

Referring to FIG. 7 , the guard-rail candidate detection unit 150 maydetect guard-rail candidate voxels satisfying the planeness indicated aswhite color except the vehicle V among the directional representativevoxels. Since there may be other objects except the guard-rail among theguard-rail candidate voxels satisfying the planeness, the guard-raildetection device 100 may detect the guard-rail through additionalclassification afterwards.

Then, the guard-rail detection unit 160 may be formed by connecting theguard-rail candidate voxels detected by the guard-rail candidatedetection unit 150 in an extended direction by connecting adjacentvoxels using a conventional clustering technique. Meanwhile, theguard-rail detection unit may connect guard-rail candidate voxels ofwhich a distance between guard-rail candidate voxels is within apredetermined distance.

The guard-rail detection unit 160 may detect at least one connectedguard-rail candidate voxel as a guard-rail candidate. By using thecharacteristics of the guard-rail that it has a constant shape and has arelatively narrow width and a relatively long length, the guard-raildetection unit 160 may detect a guard-rail candidate having a widthequal to or less than a predetermined width and a length equal to orlarger than a predetermined length as the guard-rail among the at leastone guard-rail candidate. Here, the width of the guard-rail candidatemay indicate a width in a direction parallel to the ground andperpendicular to the extended direction, and the length of theguard-rail may indicate the length in the extended direction.

The size of the guard-rail including the width and the length may varywith the shape of the guard-rail or the road condition. For example, theguard-rail detection unit 160 may detect a guard-rail candidate having awidth of 1 meter or less and a length of 25 meters or above as theguard-rail.

FIG. 8 illustrates the guard-rail detected according to the embodimentof the present disclosure.

Referring to FIG. 8 , the guard-rail detection unit 160 may finallydetect the guard-rail candidate having a width of 1 meter or less and alength of 25 meters or above as the guard-rail 300 among the guard-railcandidates.

FIG. 9 is a block diagram for explaining the guard-rail detection devicein aspect of hardware.

Referring to FIG. 1 and FIG. 9 , the guard-rail detection device 100 mayinclude a storage device 191 for storing at least one command, aprocessor 192 for executing the at least one command of the storagedevice 191, a transceiver device 193, an input interface device 194, andan output interface device 195.

Each of the components 191, 192, 193, 194, 195 included the guard-raildetection device 100 may communicate with each other by data bus 196.

The storage device 191 may include at least one of a memory, a volatilestorage medium, or a non-volatile storage medium. For example, thestorage device 191 may include at least one of a read only memory (ROM)or a random access memory (RAM).

The storage device 191 may further include at least one command to beexecuted by the processor 192, and may store therein information about ashape of the guard-rail input by a user from the input interface device194, a position of a generated voxel, point data, and so on.

The processor 192 may be implemented by a central processing unit (CPU),a graphics processing unit (GPU), a micro controller unit (MCU), or adedicated processor by which methods according to embodiments of thepresent disclosure are performed.

Referring to FIG. 1 , as described above, the processor 192 may performthe functions of the ground elimination unit 110, the voxel generationunit 120, the representative point detection unit 140, the guard-railcandidate detection unit 150 and the guard-rail detection unit 160, byat least one program command stored in the storage device 191, and eachfunction may be performed by the processor with being stored in a memoryin the form of at least one module.

The transceiver device 193 may transmit or receive data from an internaldevice or an external device connected by communication, and perform thefunction of point data receiving unit 110. For example, the transceiverdevice 193 may receive point data acquired from the lidar sensor 200.

The input interface device 194 may receive input of at least one controlsignal or set number from a user. For example, the input interfacedevice 194 may receive a reference of a shape including a width and alength of the guard-rail, or receive a user input such as a command forstarting the guard-rail detection.

The output interface device 195 may output and show at least oneinformation including a position of the guard-rail by the operation ofthe processor 192.

The guard-rail detection device according to an embodiment of thepresent disclosure has been explained.

From now on, a method for detecting the guard-rail performed by theoperation of the processor inside the guard-rail detection deviceaccording to another embodiment of the present disclosure.

FIG. 10 is a flowchart of a method for detecting the guard-railaccording to the embodiment of the present disclosure.

Referring to FIG. 1 , FIGS. 2A and 2B, and FIG. 10 , the transceiverdevice 193 may acquire data from the lidar sensor 200 (S100).

The processor 192 may detect points on the ground using the knowntechniques such as a plane fitting and a ground detection based on agrid map, based on the acquired point data, and may eliminate the pointson the ground (S200).

Then, the processor 192 may generate voxels forming a sphere around thelidar sensor 200 or the vehicle, and arrange points that are notpositioned on the ground among the points acquired from the lidar sensor200 (S300).

The processor 192 may detect directional representative points based onthe arranged points and the generated voxels (S400, S500).

Then, the processor 192 may determine whether each directionalrepresentative voxel satisfies the planeness by determining whether eachdirectional representative voxel satisfies a line fitting in the thetadirection and a line fitting in the phi direction, and detect thedirectional representative voxels satisfying the planeness as theguard-rail candidate voxels (S600).

The processor 192 may detect the guard-rail candidates by connectingadjacent guard-rail candidate voxels, and detect the guard-railcandidates satisfying a predetermined reference of a width and a lengthas the guard-rail on the road (S700, S800).

Thus, in accordance with the device and the method according to theembodiments of the present disclosure, by detecting the position of theguard-rail around the vehicle by units of voxels, it is possible toeasily and rapidly detect the position of the guard-rail on the roadwithout using all of the point data acquired from the lidar sensor.

The combinations of respective blocks of block diagrams and respectivesequences of a flow diagram attached herein is carried out by computerprogram instructions which are executed through various computer meansand recorded in a non-transitory computer-readable recording medium.Since the computer program instructions is loaded in processors of ageneral purpose computer, a special purpose computer, or otherprogrammable data processing apparatus, the instructions, carried out bythe processor of the computer or other programmable data processingapparatus, create means for performing functions described in therespective blocks of the block diagrams or in the respective sequencesof the sequence diagram. Since the computer program instructions, inorder to implement functions in specific manner, is stored in a memoryunit, which comprises non-transitory computer-readable medium, useableor readable by a computer or a computer aiming for other programmabledata processing apparatus, the instruction stored in the memory unituseable or readable by a computer produces manufacturing items includingan instruction means for performing functions described in therespective blocks of the block diagrams and in the respective sequencesof the sequence diagram. Since the computer program instructions areloaded in a computer or other programmable data processing apparatus,instructions, a series of sequences of which is executed in a computeror other programmable data processing apparatus to create processesexecuted by a computer to operate a computer or other programmable dataprocessing apparatus, provides operations for executing functionsdescribed in the respective blocks of the block diagrams and therespective sequences of the flow diagram. The computer programinstructions are also performed by one or more processes or specificallyconfigured hardware (e.g., by one or more application specificintegrated circuits or ASIC(s)). The non-transitory computer-readablerecording medium includes, for example, a program command, a data file,a data structure and the like solely or in a combined manner. Theprogram command recorded in the medium is a program command speciallydesigned and configured for the present disclosure or a program commandknown to be used by those skilled in the art of the computer software.The non-transitory computer-readable recording medium includes, forexample, magnetic media, such as a hard disk, a floppy disk and amagnetic tape, optical media, such as a CD-ROM and a DVD,magneto-optical media, such as a floptical disk, and hardware devicesspecially configured to store and execute program commands, such as aROM, a RAM, a flash memory and the like. The program command includes,for example, high-level language codes that can be executed by acomputer using an interpreter or the like, as well as a machine codegenerated by a compiler. The hardware devices can be configured tooperate using one or more software modules in order to perform theoperation of the present disclosure, and vice versa. In someembodiments, one or more of the processes or functionality describedherein is/are performed by specifically configured hardware (e.g., byone or more application specific integrated circuits or ASIC(s)). Someembodiments incorporate more than one of the described processes in asingle ASIC. In some embodiments, one or more of the processes orfunctionality described herein is/are performed by at least oneprocessor which is programmed for performing such processes orfunctionality.

Moreover, the respective blocks or the respective sequences in theappended drawings indicate some of modules, segments, or codes includingat least one executable instruction for executing a specific logicalfunction(s). In several alternative embodiments, it is noted that thefunctions described in the blocks or the sequences run out of order. Forexample, two consecutive blocks and sequences are substantially executedsimultaneously or often in reverse order according to correspondingfunctions.

The explanation as set forth above is merely described a technical ideaof the exemplary embodiments of the present disclosure, and it will beunderstood by those skilled in the art to which this disclosure belongsthat various changes and modifications is made without departing fromthe scope and spirit of the claimed invention as disclosed in theaccompanying claims. Therefore, the exemplary embodiments disclosedherein are not used to limit the technical idea of the presentdisclosure, but to explain the present disclosure. The scope of theclaimed invention is to be determined by not only the following claimsbut also their equivalents. Specific terms used in this disclosure anddrawings are used for illustrative purposes and not to be considered aslimitations of the present disclosure. Therefore, the scope of theclaimed invention is construed as defined in the following claims andchanges, modifications and equivalents that fall within the technicalidea of the present disclosure are intended to be embraced by the scopeof the claimed invention.

1. A method for detecting a guard-rail on a road, which is performed bya guard-rail detection device, the method comprising: acquiring pointsaround a lidar sensor from the lidar sensor; detecting ground pointsbased on the acquired points; arranging, among the acquired points,first points that are different from the detected ground points invoxels forming a sphere; and detecting the guard-rail based on thevoxels and the first points.
 2. The method of claim 1, wherein thedetecting of the guard-rail comprises: generating a plurality of voxelgroups by classifying voxels, having a same theta direction coordinateand a same phi direction coordinate, as a same group among the voxels inwhich the first points are arranged; selecting the closest voxel fromthe lidar sensor among the voxels in each of the plurality of voxelgroups as a directional representative voxel for each of the pluralityof voxel groups; determining whether the respective directionalrepresentative voxels for the plurality of voxel groups satisfyplaneness; selecting, among the respective directional representativevoxels for the plurality of voxel groups, directional representativevoxels satisfying planeness as guard-rail candidate voxels; andselecting a guard-rail candidate by connecting the guard-rail candidatevoxels.
 3. The method of claim 2, wherein the determining of whether therespective directional representative voxels for the plurality of voxelgroups satisfy planeness comprises: selecting, among a plurality ofpoints positioned in each of the respective directional representativevoxels for the plurality of voxel groups, a directional representativepoint for each of the directional representative voxels.
 4. The methodof claim 3, wherein the determining of whether the respectivedirectional representative voxels for the plurality of voxel groupssatisfy planeness comprises: for each of the directional representativevoxels, selecting a first voxel that is a directional representativevoxel having a same phi direction coordinate as the correspondingdirectional representative voxel and having a theta direction coordinatethat is larger than that of the corresponding directional representativevoxel, and a second voxel that is a directional representative voxelhaving a same phi direction coordinate as the corresponding directionalrepresentative voxel and having a theta direction coordinate that issmaller than that of the corresponding directional representative voxel,and determining whether the corresponding directional representativevoxel satisfies a line fitting condition for a first straight linegenerated by a predetermined first rule in the theta direction;selecting a third voxel that is a directional representative voxelhaving a same theta direction coordinate as the correspondingdirectional representative voxel and having a phi direction coordinatethat is larger than that of the corresponding directional representativevoxel, and a fourth voxel that is a directional representative voxelhaving a same theta direction coordinate as the correspondingdirectional representative voxel and having a phi direction coordinatesmaller than that of the corresponding directional representative voxel,and determining whether the corresponding directional representativevoxel satisfies a line fitting condition for a second straight linegenerated by a predetermined second rule in the phi direction; and whenthe corresponding directional representative voxel satisfies the linefitting condition for the first straight line and the line fittingcondition for the second straight line, determining that thecorresponding directional representative voxel satisfies planeness. 5.The method of claim 4, wherein the first straight line is generated byconnecting the directional representative point of the first voxel andthe directional representative point of the second voxel, and whereinthe determining of whether the corresponding directional representativevoxel satisfies the line fitting condition for the first straight linecomprises: determining that the corresponding directional representativevoxel satisfies the line fitting condition for the first straight linewhen a distance between the directional representative point of thecorresponding directional representative voxel and the first line isequal to or less than a predetermined distance.
 6. The method of claim4, wherein the second straight line is generated by connecting thedirectional representative point of the third voxel and the directionalrepresentative point of the fourth voxel, and wherein the determining ofwhether the corresponding directional representative voxel satisfies theline fitting condition for the second straight line comprises:determining that the corresponding directional representative voxelsatisfies the line fitting condition for the second straight line when adistance between the directional representative point of thecorresponding directional representative voxel and the second line isequal to or less than a predetermined distance.
 7. The method of claim4, wherein the first voxel and the second voxel are adjacent to thecorresponding directional representative voxel, and the third voxel andthe fourth voxel are adjacent to the corresponding directionalrepresentative voxel.
 8. The method of claim 2, wherein the guard-railcandidate selected in the selecting of the guard-rail candidate isformed by connecting the guard-rail candidate voxels adjacent to eachother in an extended direction.
 9. The method of claim 8, furthercomprising: detecting, as the guard rail, the guard-rail candidatehaving a width in a direction parallel to a ground and perpendicular tothe extended direction and having a length in the extended direction,the width being equal to or less than a predetermined width and thelength being equal to or larger than a predetermined length.
 10. Aguard-rail detection device comprising: a lidar sensor configured toacquire points around the lidar sensor; and a processor configured todetect ground points based on the acquired points, arrange, among theacquired points, first points that are different from the detectedground points in voxels forming a sphere, and detect a guard-rail basedon the voxels and the first points.
 11. A non-transitorycomputer-readable storage medium storing computer-executableinstructions which cause, when executed by a processor, the processor toperform a method for detecting a guard-rail on a road by using aguard-rail detection device, the method comprising: acquiring pointsaround a lidar sensor from the lidar sensor; detecting ground pointsbased on the acquired points; arranging, among the acquired points,first points that are different from the detected ground points invoxels forming a sphere; and detecting the guard-rail based on thevoxels and the first points.
 12. The non-transitory computer-readablestorage medium of claim 11, wherein the detecting of the guard-railcomprises: generating a plurality of voxel groups by classifying voxels,having a same theta direction coordinate and a same phi directioncoordinate, as a same group among the voxels in which the first pointsare arranged; selecting the closest voxel from the lidar sensor amongthe voxels in each of the plurality of voxel groups as a directionalrepresentative voxel for each of the plurality of voxel groups;determining whether the respective directional representative voxels forthe plurality of voxel groups satisfy planeness; selecting, among therespective directional representative voxels for the plurality of voxelgroups, directional representative voxels satisfying planeness asguard-rail candidate voxels; and selecting a guard-rail candidate byconnecting the guard-rail candidate voxels.
 13. The non-transitorycomputer-readable storage medium of claim 12, wherein the determining ofwhether the respective directional representative voxels for theplurality of voxel groups satisfy planeness comprises: selecting, amonga plurality of points positioned in each of the respective directionalrepresentative voxels for the plurality of voxel groups, a directionalrepresentative point for each of the directional representative voxels.14. The non-transitory computer-readable storage medium of claim 13,wherein the determining of whether the respective directionalrepresentative voxels for the plurality of voxel groups satisfyplaneness comprises: for each of the directional representative voxels,selecting a first voxel that is a directional representative voxelhaving a same phi direction coordinate as the corresponding directionalrepresentative voxel and having a theta direction coordinate that islarger than that of the corresponding directional representative voxel,and a second voxel that is a directional representative voxel having asame phi direction coordinate as the corresponding directionalrepresentative voxel and having a theta direction coordinate that issmaller than that of the corresponding directional representative voxel,and determining whether the corresponding directional representativevoxel satisfies a line fitting condition for a first straight linegenerated by a predetermined first rule in the theta direction;selecting a third voxel that is a directional representative voxelhaving a same theta direction coordinate as the correspondingdirectional representative voxel and having a phi direction coordinatethat is larger than that of the corresponding directional representativevoxel, and a fourth voxel that is a directional representative voxelhaving a same theta direction coordinate as the correspondingdirectional representative voxel and having a phi direction coordinatesmaller than that of the corresponding directional representative voxel,and determining whether the corresponding directional representativevoxel satisfies a line fitting condition for a second straight linegenerated by a predetermined second rule in the phi direction; and whenthe corresponding directional representative voxel satisfies the linefitting condition for the first straight line and the line fittingcondition for the second straight line, determining that thecorresponding directional representative voxel satisfies planeness. 15.The non-transitory computer-readable storage medium of claim 14, whereinthe first straight line is generated by connecting the directionalrepresentative point of the first voxel and the directionalrepresentative point of the second voxel, and wherein the determining ofwhether the corresponding directional representative voxel satisfies theline fitting condition for the first straight line comprises:determining that the corresponding directional representative voxelsatisfies the line fitting condition for the first straight line when adistance between the directional representative point of thecorresponding directional representative voxel and the first line isequal to or less than a predetermined distance.
 16. The non-transitorycomputer-readable storage medium of claim 14, wherein the secondstraight line is generated by connecting the directional representativepoint of the third voxel and the directional representative point of thefourth voxel, and wherein the determining of whether the correspondingdirectional representative voxel satisfies the line fitting conditionfor the second straight line comprises: determining that thecorresponding directional representative voxel satisfies the linefitting condition for the second straight line when a distance betweenthe directional representative point of the corresponding directionalrepresentative voxel and the second line is equal to or less than apredetermined distance.
 17. The non-transitory computer-readable storagemedium of claim 14, wherein the first voxel and the second voxel areadjacent to the corresponding directional representative voxel, and thethird voxel and the fourth voxel are adjacent to the correspondingdirectional representative voxel.
 18. The non-transitorycomputer-readable storage medium of claim 12, wherein the guard-railcandidate selected in the selecting of the guard-rail candidate isformed by connecting the guard-rail candidate voxels adjacent to eachother in an extended direction.
 19. The non-transitory computer-readablestorage medium of claim 18, wherein the method further comprisesdetecting, as the guard rail, the guard-rail candidate having a width ina direction parallel to a ground and perpendicular to the extendeddirection and having a length in the extended direction, the width beingequal to or less than a predetermined width and the length being equalto or larger than a predetermined length.